What is this

[jocephus30]

The previous owner did a bunch of improvements to my truck and im trying to figure it all out. I think this may have something to do with the old trailer brake system on the truck. I am getting ready to redo brakes but didnt want to mess anything up by removing this piece. Any info at all is welcome

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[Knuckledragger]

Without knowing anything else, I would guess it is indeed a trailer brake actuator. The segmented bar is connected to the differential? That lets the brakes know the truck is stopping and activates the trailer brakes.

Is there a fluid or electric connection at the hitch?

 

[riotwarrior]

Load sensing proportioning valve. When truck is loaded it squats down allowing more brake pressure to rear wheels. DO NOT REMOVE!!!!

JM2CW

Al

 

[jocephus30]

It is fluid connection and what your saying sounds right there is a piece that does bolt to the diff. There is a controler in cab that has a hard brakeline coming from it.

 

[jocephus30]

Thank you riot thats exactly what i was worried about removing it and messing something up

 

[Knuckledragger]

Load sensing proportioning valve. When truck is loaded it squats down allowing more brake pressure to rear wheels. DO NOT REMOVE!!!!

Thanks, Al. I should have spent less time trying to figure out what it would do for a trailer.

My trucks don't have these, is it on F350 and bigger, or special equipment packages?

 

[jocephus30]

Its on a 1986 crewcab dually f350 spent most of its life hauling a camper.

 

[gandalf]

Al has it right. That's the brake proportioning system. I have one just like it on my '86 F250 in Maine. They were replaced at some point with a different system.

I can't really tell you whether they were effective. My '86 had very poor braking qualities whether it was empty or loaded.

 

[riotwarrior]

... There is a controler in cab that has a hard brakeline coming from it.

That hard line to controler comes from the Master Cyl there should be a T on the MC someplace that has that line to brake controler.

Then a wire goes to rear of truck from controller to actuate magnetic brakes on trailers.

Some controllers only have capability to control one axle some multiple. A check on the brand of controllers web site should provide that information. Always use the correct controller for your application,

Also NOT all brake controllers are hydraulically actuated, some have a sensor for G force and are electronic in nature or have a pendulum. Mounting the non hydraulic ones may require a certain way of being mounted for correct operation and referring to the instructions is best. DON"T just throw it in expecting it to work.


Hope this helps!

 

[jocephus30]

Gandalf i hear you there found this thing when my master cylinder went out but i feel the same it turned up or off nerver really felt a difference. Roit thank you now its making so much sence i saw that wierd t you spoke of and thats where the line ran back.to this valve. Im replacing both wheel cylinders when I do the brakes do i need to anything special with this or just make sure system is full of fluid?

 

[riotwarrior]

Gandalf i hear you there found this thing when my master cylinder went out but i feel the same it turned up or off nerver really felt a difference. Roit thank you now its making so much sence i saw that wierd t you spoke of and thats where the line ran back.to this valve. Im replacing both wheel cylinders when I do the brakes do i need to anything special with this or just make sure system is full of fluid?

Just bleed the brakes properly, in order!

RH Rear
LH Rear
RH Front
LH Front

Don't forget to bleed the trailer brake controller too there is likely a bleed screw on the back where brake line enters...I'd suggest saving this part for last bleed!!

JM2CW

Al

 

[jocephus30]

Sounds good thank you so much for the advice